Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1997-07-28
2001-05-29
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S002000, C522S009000, C522S026000, C522S063000, C522S072000, C522S075000, C522S913000, C156S336000, C156S328000, C156S275500, C156S275100, C156S275300, C156S272200
Reexamination Certificate
active
06239190
ABSTRACT:
This invention relates to particularly but not exclusively, the effective “setting” or “curing” of an adhesive and more particularly still to effecting the setting of a tissue bonding adhesive or sealant.
WP 92/02238 discloses compositions of various predominantly ‘biological’ adhesives to bond separated tissues together or to coat tissues or prosthetic material, to enhance strength and water-tightness upon the application of energy and particularly compositions activated by radiation not least laser radiation. Thus a stronger bio-compatible bond or coating is formed. The formation of such a bond or coating being referred to generally hereinafter as “setting” the adhesive.
Such adhesives may be used instead of suturing and stapling for example in surgical procedures for repair or the creation of anastomoses.
The application of a suitable biocompatible adhesive offers many advantages to patient and surgeon alike. It avoids penetration of tissues by needles, as well as immediately sealing the treated tissue. It would prevent or minimize foreign body reaction and scarring. Such a suitable substance could be quicker to apply and may well be more accurate than standard suturing—particularly where small vessels or sutures are concerned. There is also the potential advantage, that if the “setting” energy is sufficiently low, analgesic may not be required. There are many different applications for such a material, not only for bonding anastomoses but also for dressings, hemostats and sealants.
The ‘ideal’ adhesive would be non-toxic and biocompatible, strong and supple. It would not unduly swell after setting, would be user-friendly to apply and would be easy to sterilize and prepare.
WO 92/02238 refers to prior art fibrin adhesives as well as other multicomponent adhesives. It suggests essentially a two main component adhesive comprising natural or synthetic peptides. These proteins/peptides may be modified ansymetically, chemically or otherwise. They may thus be shortened/cleaved, cross-linked, oxidized or hydrolysed, as a whole or be derivatives of subunits thereof. The original protein with or without modification may be added to by fibrous or structural proteins—for example synthetic or natural collagen, elastin keratin, fibrin, fibronactin and others. Examples of serum proteins, albumin, various globulins and others are given. All these proteins or their derivatives or additives act as the first component constituents.
The second component is said to be generally selected from constituents supporting the first component, such as forming a matrix, gel or sol therewith, usually natural or synthetic proteoglycens, glycoproteins, saccharides, gelatins or polyalcohols and others. Again these components may be modified. Micropolysaccharides, typically glysoaminoglycans including hyaluroric acid its salts, chondroitin sulphate, heparan sulphate may be incorporated.
Other additives may be used, examples being polyvalent cations eg. calcium. These may act as bonding enhancers. Additional components such as pH modifiers, citric acid, ascorbic acid may be used together with preservatives, surfactants and EDTA. The composition of these ingredients and others may be modified in concentration and variations in the molecular weight of constituents also altered to suit the application and the purpose. Viscosity may be changed from liquid to a viscous gel. Additions of non-Newtonian fluids may offer altered physical properties such as pseudoplasticity which may change a relatively viscous material to a liquid under shear forces eg. by syringe injection.
In some circumstances the combination of peptides and other previously mentioned constituents may spontaneously set, thus for example uniting arterial edges to form a ‘weld’. In other cases it is necessary to activate the composition with energy and/or photons. Whilst a variety of energy/photon sources have been proposed, most preferable are lasers, including those in the visible or IR ranges, a number of such are mentioned including Nd:YAG and Argon Lasers. UV sources may also be used. A major advantage of lasers is the precise application of laser energy to selected areas, made possible by the coherent nature and hence narrow beam feature of laser emission. Importantly the beam can be very easily and conveniently directed even to difficult access surgical sites by using optical fibre arrangements.
The use of endogenous or exogenous chromophores significantly enhance laser use. Incorporating suitable chromophores into the adhesive has several advantages. The chromophores, of which many have been quoted and used, selectively absorb the laser light energy and convert that energy to thermal energy where it has been applied. The chromophore is chosen for any specific wavelength. The heat generated then sets the adhesive. Thus chromophores enhance accuracy and distribute setting energy. Suitably chosen chromophores will also help reach setting temperatures quickly, thus reducing the time factor for laser application and importantly the overall energy requirements. On account of the selectivity of the chromophores for any given wavelength and the accuracy of such a system, thermal injury to tissue is significantly reduced or avoided.
The benefits of the combination of chromophores and laser may be further enhanced by partially setting the adhesive before ultimate application. This further reduces the final setting energy levels and has obvious clinical advantages.
There are a few major potential problems using lasers for bonding or motivating adhesives or indeed using other energy sources. The time taken for setting or bonding is usually a few seconds. Exposure of just a few more seconds may damage the underlying tissue being treated or other surrounding tissue. The operator will usually see a faint glow when the appropriate setting temperature has been obtained. However this is unreliable and indeed may be difficult in taxing surgical application or conditions. It is thus relatively easy for the operator to either under-irradiate or over-irradiate.
This invention describes the use of “colour change” chromophores which will demonstrate to the operator that the suitable end point has been reached. More importantly, the invention gives further protection and confidence to the operator by comprising of a method, effecting such a reaction by irradiating a substance which absorbs the radiant energy until the reaction is sufficiently complete and the absorbence of the material changes so as to significantly reduce or cease absorption of further energy. Thus not only has the end point been clarified, but also safety as been enhanced by reducing the possibility of further potentially damaging energy being absorbed.
The reaction may comprise the setting of an adhesive such as a composition which bonds to living or other tissue or other materials. In the living tissue situation the components may be modified to enhance structural heating and to encourage cellular ingrowth.
The substance with or without additional components may comprise of a chromophore or group of chromophores which changes per se following irradiation or which reacts with another substance eg. ascorbic acid, to change in the conditions brought about by irradiation.
The method may be used to effect setting of an adhesive or potential adhesive applied to living or other tissue, in which the adhesive is irradiated with radiation which is poorly absorbed by the tissue but well absorbed by the adhesive until it changes colour, which prevents undesirable effects as a consequence of over-irradiation.
The substance may be irradiated by laser light to effect the reaction, which may be in the IR, visible or UV region of the spectrum. The choice of wavelength and chromophore may be altered for different applications.
The Argon laser at 488 and 514 nm is suitable for many applications. Laser power output may be altered, 0.15 W-0.3 W being commonly used. Power may be reduced to 0.05 W in thermally pre-treated adhesives, eg. pre-treatment in which the material is incubated to approximately 70% of setting
Mandley David John
Wilkinson Francis
Frost Brown Todd LLC
McClendon Sanza L.
Seidleck James J.
Tissuemed Limited
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